2D binaural sound localization: For urban search and rescue robotics

Being able to localize the position of a sound source is an important issue in robotics and many other application areas, since it enables those systems to interact with the environment. For example, USAR robotics can use sound to search for hidden victims that are shouting for help. The 2D binaural sound localization system in this paper is inspired by the human auditory system and is based on the lnteraural Time Difference (lTD) and the Head Related Transfer Function (HRTF). The lTD is used to localize a sound source in the horizontal plane relaying on the difference of arrival times of the sound signal between the two microphones and notches in frequency spectra (HRTF) are used to localize a sound source in the vertical plane. To easily and accurately extract notches we used a spiral shaped pinna that allows notches in t he frequency spectra to change linearly as a sound source moves in t he vertical plane, giving a relationship between notches and elevation angle. The two models used in this paper are tested to assess their accuracy, show their limitations and we concluded by noting how accuracy and repeatability can be improved.